OFFSET
0,2
COMMENTS
This was the original version of A126936.
FORMULA
T(n,n) = A069722(n+1) for n >= 0.
Bivariate o.g.f.: Sum_{n,k >= 0} T(n,k)*x^n*y^k = -1/sqrt(1 - 4*x) + sqrt((1 + y)/(1 - 8*x*(1 + y))/(y + sqrt(1 - 8*x*(1 + y)))).
EXAMPLE
Table T(n,k) (with rows n >= 0 and columns k = 0..n) begins as follows:
0;
4, 4;
36, 60, 24;
288, 688, 560, 160;
2240, 7080, 8760, 5040, 1120;
17304, 68712, 114576, 99456, 44352, 8064;
133672, 642824, 1351840, 1572480, 1055040, 384384, 59136;
...
MATHEMATICA
t[l_, m_] := Sum[2^k*Binomial[2*m-2*k, m-k]*Binomial[m+k, m]*Binomial[k, l], {k, 1, m}]; Table[t[l, m], {m, 0, 11}, {l, 0, m}] // Flatten (* Jean-François Alcover, Jan 09 2014_ from the original version of A126936 *)
PROG
(PARI) T(n, k) = sum(j=1, n, 2^j*binomial(2*n-2*j, n-j)*binomial(n+j, n)*binomial(j, k));
tabl(nn) = {for (n=0, nn, for (k=0, n, print1(T(n, k), ", "); ); print(); ); }
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Petros Hadjicostas, May 25 2020
STATUS
approved